Medical care of individuals requires the widespread use of catheter devices for taking blood samples, for intravenous (IV) drug delivery, and for the introduction or removal of other fluids. The use of a catheter device (hereinafter, “catheter”) typically involves first inserting a needle and plastic catheter combination into the vein of a patient and then removing the needle to leave only the plastic catheter in the vein. The withdrawn needle is then typically disposed of.
To assist in the disposal process and to help prevent health care workers from becoming injured when coming in contact with an exposed tip of a used needle, needle guards have been developed to block the tip of a needle after it has been withdrawn. Indeed, with potentially fatal infectious diseases, such as Acquired Immune Deficiency Syndrome (AIDS) and hepatitis which can be transmitted through the exchange of body fluids by accidental contact with the needle tip of a used needle, needle stick protection has never been more important.
Commercially available safety catheter devices generally may be grouped into three basic categories: (1) those which include an activation mechanism to hide the withdrawn needle within a needle shield; (2) those which require placement of a separate needle guard; and (3) those which include a sliding shield which must be manually positioned distally over the used needle. Despite their laudable intentions, most of these safety catheter devices suffer from some shortcomings. Among other things, some require an extra step beyond the normal insertion and withdrawal steps and/or require additional complicated pieces to ensure that the needle guard and the catheter remain attached during the withdrawal procedure.
Of the first category, there are several different conventional systems available with a common design which utilizes a frictionally locked spring biased needle shield to automatically engage the needle tip when the needle is withdrawn from the catheter. While these devices may be considered adequate, a user can unknowingly apply sufficient force during the withdrawal process to overcome the frictional engagement in the device so that the spring biased shield can slip off of the distal end of the needle and leave the needle tip exposed.
Another example of the first category prior art spring biased needle shield utilizes a slightly expanded portion of the needle tip (such as a protrusion or a crimped surface) to prevent the needle shield from sliding off of the distal end of the needle once the shield has engaged. In many of these designs, the needle shield is first frictionally positioned in the catheter body before use or insertion into a patient's vein. However, after insertion and during the withdrawal process, the frictionally positioned shield has a tendency to disengage from the catheter body before complete separation of the needle from the catheter. When this occurs, the needle tip is left exposed due to the early separation of the spring shield.
In conventional prior art devices of the second and third categories, there are a number of different designs which include needle shields with either a spring-clip fitting or a frictional fitting. A needle shield of this type is either placed directly on the needle tip or is movable from the base of the needle to the tip of the needle along the longitudinal direction of the needle. In the latter embodiment, a user can manually slide the needle shield towards the needle tip to engage the needle shield thereto. However, these manually activated designs require that the user either slide or apply the needle shield to the tip of the needle by hand, thus significantly raising the risk of unintentional contact with the needle tip.
In another prior art catheter assembly, the safety guard is configured to sit in the catheter hub until the needle is withdrawn. Once the needle is withdrawn, the safety guard automatically unlocks from the catheter hub to block the needle tip. This design, however, adds an inherent adverse drag between the needle and the safety guard as the needle is withdrawn. This drag is undesirable because it can create an uneven withdrawal movement.
Accordingly, there remains a need for a catheter assembly which reduces the risk of early disengagement by both holding the needle shield and the catheter body together during the withdrawal process and simultaneously and automatically disengaging from the catheter body with substantially zero adverse drag and blocking the needle tip once the withdrawal process is complete.